The Present invention relates to conveyers, and more particularly to an improved structure of roller conveyer which produce low noise during its operation.
FIG. 1 shows a roller conveyer according to the Prior art which comprises a power rack, two track and roller units bilaterally mounted on the power rack at its top side and driven to carry things forwards. Each track and roller unit comprises a conveying chain, and a plurality of rollers revolvably supported between links of the chain. This structure of roller conveyer has drawbacks. Because the rollers are revolvably supported between links of the chain, the chain directly bears the pressure of the load, and high noise will be produced during the operation of the roller conveyer. Because the rollers must be exposed to the outside for carrying the load, dust and small objects may fall to the inside of the track and roller units , causing the chains to be stuck. Furthermore, this design does not allow the user to change the pitch between the rollers.
The present invention has been accomplished to provide a roller conveyer which eliminates the aforesaid drawbacks. According to one aspect of the present invention, the roller conveyer comprises a power rack, a motor drive mounted in said power rack, two track and roller units bilaterally mounted on the power rack, each track and roller unit including a track, a longitudinal row of equally spaced roller assemblies mounted on the track, and a chain driven by the motor drive to turn the roller assemblies in carrying things forwards, wherein each roller assembly includes two symmetrical hollow holder frames transversely fastened to the track by screws and nuts and having a respective axle hole, two axle bearings respectively mounted in the axial holes of the hollow holder frames, an axle revolvably supported on the axle bearings between the hollow holder frames, a bushing sleeved onto the axle and stopped at one side of one axle bearing and having a collar raised around the periphery and a chain wheel fixedly mounted thereon around its periphery and meshed with the chain, an annular locating member mounted around the axle and stopped outside one hollow holder frame and having an outward flange raised around the periphery, a roller mounted around the bushing and having two opposite sides stopped between the collar of the bushing and the outward flange of the annular locating member and turned with the bushing to carrying things forwards, and a spring mounted between the roller and the annular locating member and spaced around the bushing. According to another aspect of the present invention, a dust cover is covered on each track, having a longitudinal row of openings corresponding to the rollers of the roller assemblies of the corresponding track and roller unit. According to still another aspect of the present invention, the axle bearings, the bushing and the annular locating member are made from rigid material for example engineering plastic or metal; the roller is comprised of a roller body made from rigid material, and a roller shell made from flexible material and covered around the roller body. Because the chain does not directly bear the pressure of the load, less noise is produced during the operation of the roller conveyer. Because the roller assemblies are respectively fastened to the respective tracks by screws and nuts, they can be detached from the tracks and then re-installed subject to the desired pitch.